Cs0017 Solved: Preventing Multiple Main Methods Errors

CS0017 Solved: Preventing Multiple Main Methods Errors

In C#, the entry point of a program is defined by the main() method. It is the starting point where the execution of the program begins. However, if multiple main() methods are defined within the same assembly, it can lead to a compilation error, specifically CS0017: “Program has more than one entry point defined.”

To prevent this error and ensure proper program execution, there are a few key points to consider:

  1. Unique main() Method:

    • Ensure that there is only one main() method defined within the assembly. This means that only one class can have a main() method.

    • If you have multiple source files within your project, make sure that only one of them contains the main() method.

  2. Assembly Attribute:

    • Use the [assembly: System.EntryPointAttribute(typeof(Program))] attribute to explicitly specify the entry point of your program. This attribute should be placed in the assembly-level attributes section of your project’s AssemblyInfo.cs file.

    • For example:

      [assembly: System.EntryPointAttribute(typeof(Program))]
      namespace YourNamespace
          class Program
              static void Main(string[] args)
                  // Your program logic here...
  3. Multiple Projects:

    • If your solution contains multiple projects, ensure that only one project has a main() method. The other projects should be treated as libraries or modules that are referenced by the main project.
  4. Command-Line Arguments:

    • If you need to pass command-line arguments to your program, you should define the Main() method with the following signature:

      static int Main(string[] args)
    • This allows you to access the command-line arguments passed to the program.

By following these guidelines, you can prevent the CS0017 error and ensure that your program has a well-defined entry point. Remember to always have only one main() method within your assembly to avoid conflicts and maintain a single starting point for program execution.# Cs0017 Solved: Preventing Multiple Main Methods Errors

Executive Summary

This comprehensive guide delves into the common error of having multiple main methods in a C# program and provides a detailed explanation of the background, causes, and effective solutions to avoid this issue. By understanding the underlying concepts and utilizing the provided solutions, developers can ensure that their C# programs adhere to proper coding practices, improving code readability, maintainability, and avoiding execution errors.


In the world of software development, errors are inevitable, and C# programming is no exception. One of the prevalent errors that C# developers often encounter is the “Cs0017: Program has more than one entry point” error. This error arises when a C# program contains multiple main methods, leading to compile-time failure. To address this issue, it’s crucial to understand the fundamental concepts behind the main method and the reasons why having multiple main methods is problematic.

Subtopic 1: Understanding the main Method

The main method serves as the entry point of a C# program, where execution begins. This method is mandatory for every C# program, as it’s the starting point from where the program’s logic is executed. Within the main method, developers define the program’s logic and functionality, such as input/output operations, calculations, and conditional statements.

  • Key Points:
    • A C# program can only have one main method.
    • The main method must be declared as public static void Main(string[] args).
    • The main method can be overloaded with different parameters, but only one overload can be designated as the entry point.

Subtopic 2: Causes of Multiple main Methods

Multiple main methods in a C# program can be caused by various factors. Here are some common causes:

  • Nested main Methods: Developers might inadvertently define multiple main methods within nested classes or regions, resulting in more than one entry point.
  • Incorrect Main Method Signature: If the signature of the main method does not match the required format (public static void Main(string[] args)), the compiler will generate an error.
  • Multiple Entry Point Attributes: Applying the [STAThread] or [MTAThread] attributes to multiple main methods can lead to the “Cs0017” error, as both attributes specify the entry point of the program.

Subtopic 3: Consequences of Multiple main Methods

Having multiple main methods in a C# program can lead to several negative consequences:

  • Compilation Errors: The presence of multiple main methods triggers a compile-time error, preventing the program from building successfully.
  • Inconsistent Program Behavior: If multiple entry points are allowed, the program’s behavior becomes unpredictable, making it difficult to debug and maintain.
  • Poor Readability and Maintainability: Multiple main methods hinder code readability and make it challenging to understand the program’s flow and logic.

Subtopic 4: Identifying Multiple main Methods

To identify the presence of multiple main methods in a C# program, developers can utilize various techniques:

  • Visual Studio Error Messages: The compiler displays error messages highlighting the existence of multiple main methods, indicating the location of the additional main methods.
  • Code Inspection: By thoroughly examining the codebase, developers can manually identify instances where multiple main methods are defined.
  • Static Analysis Tools: Employing static analysis tools can help detect instances of multiple main methods and other potential coding errors.

Subtopic 5: Preventing Multiple main Methods

Preventing multiple main methods in a C# program is crucial for ensuring proper execution and avoiding compilation errors. Here are several effective strategies:

  • Single Entry Point: Ensure that there is only one main method defined in the program, following the correct signature (public static void Main(string[] args)).
  • Consistent Entry Point Attributes: When using the [STAThread] or [MTAThread] attributes, ensure that only one main method is attributed, as these attributes specify the program’s entry point.
  • Properly Nested Methods: Avoid defining main methods within nested classes or regions, as this can lead to multiple entry points.


In conclusion, the “Cs0017: Program has more than one entry point” error is a common issue encountered in C# programming, arising from the presence of multiple main methods. Understanding the causes and consequences of multiple main methods is essential for developing robust and error-free C# programs. By employing the recommended solutions and adhering to proper coding practices, developers can effectively prevent this error, ensuring clean, maintainable, and error-free code.

Keyword Phrase Tags:

  • C# Programming
  • Multiple Main Methods
  • Cs0017 Error
  • Entry Point
  • Coding Best Practices
Share this article
Shareable URL
Prev Post

Fixing Cs0018: How To Handle Unexpected Symbol Errors

Next Post

Understanding Cs0016: Compilation Errors Due To Invalid Output Paths

Comments 14
  1. I have some additional information that may be helpful. In some cases, you may also need to check the classpath to ensure that there are no duplicate copies of the class file containing the main method.

  2. This is not a new error, it has been around for years. It is surprising that you are just now encountering it.

  3. I can’t believe you actually wrote an article about this. It’s such a basic error.

  4. I tried this solution and it worked! Now I can finally run my program without getting that annoying error message.

  5. I’m not sure if this solution will work for me. I’m using a different IDE.

  6. I’ve been using this solution for years and it’s never failed me.

  7. I’m not sure I understand this solution. Can someone explain it to me?

  8. I’m not sure if this solution will work for me. I’m using a different version of Java.

Comments are closed.

Read next